WO2010039008A2 - Apparatus and method for manufacturing float glass - Google Patents

Abstract

The present invention relates to a method for manufacturing float glass and a manufacturing apparatus used in said method. The manufacturing method involves suspending glass on molten tin held in a molten tin bath, and is characterised by the following steps: a) discharging a portion of said molten tin from said molten tin bath; b) removing oxygen from the discharged molten tin by spraying it with an oxygen removal gas containing hydrogen; and c) returning it to said molten tin bath.

Description

Method for manufacturing float glass and apparatus for manufacturing same

The present invention relates to a method of manufacturing a float glass and an apparatus for manufacturing the same, in which the amount of dissolved oxygen in the molten tin bath can be reduced when the glass is floated on the molten tin contained in the molten tin bath. This application claims the benefit of the filing date of Korean Patent Application No. 10-2008-0097373 filed with the Korea Patent Office on October 2, 2008, the entire contents of which are incorporated herein.

Float glass is manufactured using the conventional float process method. In other words, the molten glass is injected into the upper portion of the molten tin having a large specific gravity contained in the molten tin bath to produce a float glass that produces plate glass without irregularities.

However, in the production of plate glass using a molten tin bath, bubble defects due to oxygen of tin or oxygen dissolved in tin has become a big technical problem in the existing production method.

In order to solve this problem, a technology has been developed to maintain the atmosphere of the molten tin bath in an oxygen-free atmosphere and to prevent oxygen from dissolving inside the tin by sealing to prevent the air from entering. As it was not easy to remove the dissolved oxygen sufficiently, it was difficult to lower the product defect rate.

An object of the present invention is to float dissolved oxygen in the molten tin bath by the oxygen solubility difference according to the temperature and the oxygen of the molten tin by the oxygen removal gas containing hydrogen effectively float glass which can reduce product defects It is to provide a manufacturing method and a manufacturing apparatus thereof.

The present invention relates to a method of manufacturing a float glass in which a glass is floated on a molten tin contained in a molten tin bath to produce a float glass, the method comprising: a) discharging a part of the molten tin of the molten tin bath to the outside of the molten tin bath Doing; b) removing oxygen contained in the molten tin discharged from the molten tin bath, and spraying an oxygen removing gas including hydrogen into the molten tin to remove oxygen contained in the molten tin; And c) returning the molten tin from which the oxygen has been removed to the molten tin bath.

The present invention provides a float glass manufacturing apparatus for producing a float glass by floating the glass over the molten tin contained in the molten tin bath, molten tin bath; A discharge line connected to communicate with the inside of the molten tin bath and discharging a part of the molten tin of the molten tin bath to the outside of the molten tin bath; An oxygen removal chamber provided to be connected to the discharge line to receive the molten tin discharged from the molten tin bath through the discharge line; An injector provided inside the oxygen removal chamber and injecting an oxygen removal gas including hydrogen to the molten tin in the oxygen removal chamber; And a return line for returning the molten tin from which oxygen has been removed by the injector to the molten tin bath.

According to the present invention, as the amount of dissolved oxygen in the molten tin bath can be reduced, defects caused by tin oxides such as Tin Drop, Tin Pick-up, and Top Speck, It is possible to reduce Bottom Open Seed.

1 is a plan view of a molten tin bath according to the present invention.

2 is a cross-sectional view of the oxygen removing chamber and the heating chamber along the line A-A of FIG.

3 is a cross-sectional view of the porous member of FIG. 2.

In the method of manufacturing a float glass according to the present invention, a method of manufacturing a float glass in which a glass is floated on a molten tin contained in a molten tin bath, to produce a float glass, a) a part of the molten tin of the molten tin bath Discharging to the outside of the molten tin bath; b) removing oxygen contained in the molten tin discharged from the molten tin bath, and spraying an oxygen removing gas including hydrogen into the molten tin to remove oxygen contained in the molten tin; And c) returning the molten tin from which the oxygen has been removed to the molten tin bath.

In the present invention, the process of removing the oxygen in the molten tin is not carried out directly in the molten tin bath for producing a float glass, but by proceeding outside the molten tin bath, it is effective without affecting the production of float glass in the molten tin bath. Can remove oxygen in the molten tin.

In addition, the present invention is characterized by using a method of spraying oxygen removal into the molten tin at the same time using the oxygen removing gas when removing oxygen in the molten tin, and not simply contacting the oxygen removing gas with the surface of the molten tin. . Injecting the oxygen removal gas into the molten tin as described above may be more efficiently performed by performing oxygen removal outside the molten tin bath. That is, when oxygen removal is directly performed in the molten tin bath, spraying the oxygen removing gas into the molten tin as described above may affect the production of float glass.

In the present invention, the oxygen removal gas is not only in contact with the surface of the molten tin, but oxygen can be more efficiently removed by directly injecting the oxygen gas into the molten tin. Specifically, when the oxygen removing gas is simply in contact with the surface of the molten tin, the contact area between the oxygen removing gas and the molten tin is not only small, and the oxygen removing gas is in contact with the molten tin before removing the oxygen in the molten tin. Because it reacts first with oxygen that may be present in it, the oxygen removal efficiency is reduced. Therefore, the method according to the present invention can remove oxygen much more efficiently than the technique of simply contacting the oxygen removing gas with molten tin.

In the step a), the molten tin bath in which the molten tin is discharged is not limited, but the molten tin of the molten tin bath in the region where the temperature of the molten tin is 700 ~ 1000 ℃ of all areas of the molten tin bath Can be discharged. For example, molten tin may be discharged from a cold zone of a molten tin bath having a molten tin temperature of 600 to 800 ° C. in the molten tin bath. However, it is not limited to this.

Oxygen removal gas of step b), the flow rate is 0.2 ~ 2Nm ³ / hr, the pressure is 2 ~ 5kgf / cm ² , the temperature may be 300 ~ 500 ℃. Here, the flow rate and pressure is a value set based on the amount required for the reaction and the standard that can penetrate the porous layer, it can prevent the molten tin supercooling at the temperature. However, the present invention is not limited to the flow rate, pressure, and temperature conditions, and may be variously changed as necessary.

The oxygen removing gas of step b) may further include an inert gas. Nitrogen is mentioned as said inert gas. However, it is not limited to this.

If only pure hydrogen gas is used, hydrogen may be dissolved into the molten tin. If oxygen removal gas containing an inert gas is used together with hydrogen gas (H ₂ ), hydrogen gas may be prevented from being dissolved into the molten tin. Can be. The inert gas may be discharged to the outlet.

In the oxygen removing gas of step b), the mixing ratio of the inert gas and the hydrogen gas, based on volume, may be less than 90 ~ 100: over 0 ~ 10. Here, when the inert gas is nitrogen gas, nitrogen gas: hydrogen gas may be less than 90 ~ 100: more than 0 ~ 10. On the other hand, the nitrogen gas: hydrogen gas on a volume basis may be 90 to 100: 0 to 10.

In step b), as oxygen (H ₂ O) is generated by chemically reacting the oxygen contained in the molten tin with the hydrogen, oxygen included in the molten tin may be removed.

In addition, by lowering the temperature of the molten tin by a relatively low oxygen removal gas, there is also a physical effect of extracting dissolved oxygen by reducing the saturated solubility of oxygen contained in the molten tin.

When the oxygen removal gas is bubbled when the oxygen removal gas is brought into contact with the molten tin, extraction of the dissolved oxygen is further facilitated by bubbling the oxygen removal gas. Specifically, the bubbles of the oxygen removing gas generated by bubbling to rise by absorbing the oxygen contained in the molten tin. As such, the contact area with the molten tin can be increased by the bubbled oxygen removing gas, thereby not only making the chemical removal of dissolved oxygen in the molten tin more efficient, that is, the oxygen and hydrogen of the molten tin As water (H ₂ O) is generated by the reaction, removal of dissolved oxygen can be more efficient, and the physical effect of extracting dissolved oxygen by reducing the dissolved oxygen and saturation due to the cooling effect by the oxygen removal gas is reduced. It can also be more efficient.

The temperature of the bubbling molten tin bubbled in step b) may be 400 ~ 700 ℃.

The saturated solubility of oxygen reduced in step b) may be several tens ppm or less.

Saturation solubility of oxygen contained in the molten tin may be as shown in Table 1 below.

Table 1

 Here, the solubility is the solubility (thermodynamic data) according to the temperature, and means the maximum oxygen saturation after bubbling.

In step c), the molten tin from which the oxygen is removed may be heated and then returned to the molten tin bath.

The temperature of the heated molten tin may be 1200 ~ 1400 ℃. If the temperature is not high enough, the operating stability of the return region of the molten tin in which the glass forming starts may deteriorate.

In the step c), the molten tin from which the oxygen is removed may be returned to a region where the temperature of the molten tin is 1200 to 1400 ° C. in the entire region of the molten tin bath.

An apparatus for producing float glass according to the present invention comprises: a apparatus for producing float glass, which floats glass onto molten tin contained in a molten tin bath to produce float glass, comprising: molten tin bath; A discharge line connected to communicate with the inside of the molten tin bath and discharging a part of the molten tin of the molten tin bath to the outside of the molten tin bath; An oxygen removal chamber provided to be connected to the discharge line to receive the molten tin discharged from the molten tin bath through the discharge line; An injector provided inside the oxygen removal chamber and injecting an oxygen removal gas including hydrogen to the molten tin in the oxygen removal chamber; And a return line for returning the molten tin from which oxygen has been removed by the injector to the molten tin bath.

The discharge line may be connected to a region in which the temperature of the molten tin is 700 ~ 1000 ℃ of the entire region of the molten tin bath.

The injector may be configured to lower the temperature of the molten tin in the oxygen removing chamber to reduce the saturated solubility of oxygen contained in the molten tin so that oxygen contained in the molten tin may be removed, thereby removing oxygen including hydrogen. It may be a bubbling device for bubbling a gas to the molten tin contained in the oxygen removal chamber.

The bubbling device may supply an oxygen removal gas having a temperature of 300 to 500 ° C. at a flow rate of 0.2 to 2 Nm ³ / hr and a pressure of 2 to 5 kgf / cm ² .

The oxygen removal gas may further include an inert gas. Nitrogen is mentioned as said inert gas. However, it is not limited to this.

The mixing ratio of the inert gas and the hydrogen gas may be less than 90 to 100: greater than 0 to 10 on a volume basis. Here, when the inert gas is nitrogen gas, nitrogen gas: hydrogen gas may be less than 90 ~ 100: more than 0 ~ 10. On the other hand, nitrogen gas: hydrogen gas may be 90-100: 0-10 by volume.

The bubbling device may include a porous member, and the porous member may be formed of a ceramic material.

The hole of the porous member may be formed in a direction perpendicular to the plate surface, it may be formed inclined in one direction (see Fig. 3).

If the hole of the porous member is formed to be inclined diagonally, the floating trajectory of the bubbling oxygen removing gas passing through the porous member may be longer than the hole formed in the vertical direction, so that the bubbling oxygen removing gas floats in the molten tin ( path), ie the reaction time can be extended.

In addition, by forming a flow that can collect the tin oxide that can be suspended on the molten tin surface as possible, it is possible to easily remove the tin oxide floating layer, if the removal of the final suspended tin oxide.

The gas supply line may further include a gas supply line connected to the oxygen removing chamber and supplying the oxygen removing gas bubbled by the bubbling device into the oxygen removing chamber.

The temperature of the molten tin in the oxygen removing chamber bubbled by the bubbling device may be 400 ~ 700 ℃.

The saturated solubility of oxygen contained in the molten tin bubbled by the bubbling device may be several tens ppm or less.

As oxygen (H ₂ O) is generated by reacting oxygen contained in the molten tin with the hydrogen in the oxygen removing chamber, oxygen included in the molten tin may be removed.

The oxygen removal chamber may be provided with a discharge port through which the water (H ₂ O) is discharged to the outside of the oxygen removal chamber in the form of water vapor.

The apparatus for manufacturing float glass according to the present invention may further include a heating chamber provided to be connected to the oxygen removing chamber and including a heating device for heating molten tin from which oxygen is removed from the oxygen removing chamber.

In this case, the return line may be connected to the heating chamber and the molten tin bath to return the molten tin heated in the heating chamber to the molten tin bath.

The temperature of the molten tin heated in the heating chamber may be 1200 ~ 1400 ℃.

The heating chamber and the oxygen removal chamber may be separately provided and connected to each other, or the heating chamber and the oxygen removing chamber may be integrally divided into partitions of the heating chamber and the oxygen removing chamber by partition walls.

The partition wall may be formed with a through hole so that the molten tin from which the oxygen is removed from the oxygen removal chamber may be moved to the heating chamber.

The through hole may be formed in the partition wall so as to be positioned at a position lower than the level of the molten tin contained in the oxygen removing chamber. Preferably, the through hole is formed at a position that is immersed in the molten tin.

As the molten tin is bubbled in the oxygen removal chamber, the temperature of the molten tin decreases, and thus, tin oxide may be generated on the surface and floated. The floating tin oxide layer passes through the through hole to the heating chamber. In order to prevent that, the through hole is preferably formed at a position lower than the level of the molten tin, for example, soaked in the molten tin.

As an example, the through hole may be formed in the partition wall at a predetermined height from the bottom surface of the chamber.

The return line may return the molten tin from which oxygen has been removed to a region where the temperature of the molten tin is 1200 to 1400 ° C. in all regions of the molten tin bath.

As described above, according to the method and apparatus of the present invention, a chemical reaction in which water (H ₂ O) is generated by reaction of oxygen and hydrogen in molten tin by using a method of directly injecting an oxygen removing gas into molten tin and directly contacting it Not only can the dissolved oxygen be removed, but the dissolved oxygen in the molten tin can be discharged due to the difference in solubility by the relatively low temperature oxygen removing gas, thereby reducing the amount of dissolved oxygen in the molten tin bath. Functions also occur.

In particular, when using the method of bubbling the oxygen removal gas when the oxygen removal gas is in contact with the molten tin, extraction of the dissolved oxygen is more easily facilitated by bubbling the oxygen removal gas. Specifically, the bubble of the oxygen removing gas generated by bubbling is to rise to absorb the oxygen contained in the molten tin. As described above, the bubbling oxygen removal gas has a larger contact area with molten tin, and thus, the chemical removal of dissolved oxygen of the molten tin, that is, by the reaction of oxygen and hydrogen in the molten tin, generates water (H ₂ O). Not only does oxygen removal occur more efficiently, but also the physical function of extracting dissolved oxygen by reducing the saturation of dissolved oxygen by the cooling effect by the oxygen removal gas can be made more efficient.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

On both sides of the molten tin bath of FIG. 1, a stripping chamber including an oxygen removal chamber and a heating chamber is provided for removing oxygen dissolved in the molten tin in the molten tin bath. In FIG. 1, stripping chambers are provided on both sides of the molten tin bath, but the number and installation positions of the stripping chambers are not limited to those illustrated in the drawing.

The molten tin inlet side of each stripping chamber is connected to a discharge line for supplying molten tin discharged from the molten tin bath into the oxygen removing chamber.

The molten tin outlet side of each stripping chamber is connected to a return line connecting a heating chamber and a molten tin bath for heating the molten tin from which oxygen is removed to a predetermined level or less, such as several ppm or less of dissolved oxygen, inside the oxygen removing chamber.

The stripping chamber of FIG. 2 is a chamber in which the oxygen removal chamber and the heating chamber are integrated, and includes a partition wall, an oxygen removal chamber and a heating chamber partitioned by the partition wall.

The partition wall separates the atmosphere of the oxygen removal chamber from the atmosphere of the heating chamber to separate the atmospheric conditions favorable for oxygen removal and the atmospheric conditions for suppressing reoxidation of the molten tin from which oxygen is removed. .

The partition wall is formed with a through hole for moving the molten tin from which oxygen is removed from the oxygen removal chamber to the heating chamber.

The through hole is preferably formed in the partition wall so as to be positioned at a position lower than the level of the molten tin contained in the oxygen removing chamber. As shown in Figure 2, it is preferable that the through hole is formed at a position that is submerged in the molten tin.

The oxygen removal chamber is a region for removing oxygen contained in the molten tin discharged from the molten tin bath.

On one side of the oxygen removal chamber, a discharge line connecting the molten tin bath and the oxygen removal chamber is connected.

Here, the discharge line is not limited to the installation position unless it interferes with the molten tin flow in the molten tin bath as much as possible.

Inside the oxygen removal chamber, a bubbling device capable of blowing a mixed gas of nitrogen (N ₂ ) and hydrogen (H ₂ ), which are oxygen removal gases, into the oxygen removal chamber is provided. A gas supply line (not shown) is provided to supply the mixed gas to the oxygen removing chamber so that the mixed gas can pass through the bubbling device.

The bubbling device can be used in various ways as long as it is a porous member having mechanical and chemical durability against molten tin.

As an example, the porous member may be a porous ceramic plate having a plurality of holes. Accordingly, the mixed gas of nitrogen (N ₂ ) and hydrogen (H ₂ ) supplied into the oxygen removal chamber passes through the hole of the porous ceramic plate.

The hole of the porous member may be formed to be inclined in an oblique direction as shown in FIG. 3.

As such, the dissolved oxygen of the molten tin contained in the oxygen removal chamber may be chemically removed, that is, the molten tin by the mixed gas of nitrogen (N ₂ ) and hydrogen (H ₂ ) bubbled by the bubbling device. As the water (H ₂ O) is generated by the reaction of oxygen and hydrogen, not only can oxygen be removed, but also dissolved oxygen and saturation are reduced by the cooling effect by the mixed gas introduced into the oxygen removal chamber. The physical function of extracting is also achieved.

The water (H ₂ O) generated by the above process is converted into water vapor form in the oxygen removal region of the oxygen removal chamber and discharged through an outlet provided on the upper side of the oxygen removal chamber.

In order to match the temperature of the molten tin from which oxygen was removed from the oxygen removing chamber with the molten tin temperature of the molten tin bath in which the glass is being formed, the heating chamber is used to heat the molten tin that has passed through the oxygen removing chamber at a predetermined temperature, for example, 1200 to 1400 ° C. It is a heating area to heat above.

A plurality of electric heaters are provided in the heating chamber to heat molten tin.

Here, the electric heater may use an electric heater of the same or similar type as the electric heater in the molten tin bath.

One side of the heating chamber is connected to the return line connecting the molten tin bath and the heating chamber.

The return line is preferably installed where the depth of tin is as deep as possible, for example, where the depth is 70 to 100 mm and the molten tin temperature in the molten tin bath is 1200 to 1400 ° C. The installation location is not limited unless it is disturbed as much as possible.

As described above, according to the present invention, the dissolved oxygen content of the molten tin in the molten tin bath is effectively removed by dissolving the oxygen in the molten tin by bubbling of the oxygen solubility gas and the oxygen removing gas containing hydrogen according to the temperature, thereby dissolving the dissolved oxygen. Oxygen can be reduced to several ppm or less, thereby reducing product defects.

Claims (29)

In the float glass manufacturing method for producing a float glass by floating the glass over the molten tin contained in the molten tin bath, a) discharging a part of the molten tin of the molten tin bath to the outside of the molten tin bath; b) removing oxygen contained in the molten tin discharged from the molten tin bath, and spraying an oxygen removing gas including hydrogen into the molten tin to remove oxygen contained in the molten tin; And c) returning the molten tin from which the oxygen has been removed to the molten tin bath. The method of claim 1, wherein in the step a), molten tin of the molten tin bath is discharged in a region where the temperature of the molten tin is 700 to 1000 ° C in all regions of the molten tin bath. The method of claim 1, wherein the oxygen removing gas of step b), the flow rate is 0.2 ~ 2Nm ³ / hr, the pressure is 2 ~ 5kgf / cm ² , the temperature is 300 ~ 500 ℃ manufacturing method of float glass. The method of claim 1, wherein the oxygen removing gas of step b) further comprises an inert gas. The method according to claim 4, wherein the mixing ratio of the inert gas and the hydrogen gas of the oxygen removing gas of step b) is less than 90 ~ 100: more than 0 ~ 10 on a volume basis. The method of claim 1, wherein in step b), the oxygen removal gas containing hydrogen is bubbled into the molten tin to lower the temperature of the molten tin, thereby reducing the saturated solubility of oxygen contained in the molten tin, thereby melting the molten tin. Process for producing a float glass to remove oxygen contained in the tin. The method of claim 6, wherein the temperature of the molten tin bubbling in the step b) is 400 ~ 700 ℃. The method according to claim 1, wherein in step b), the oxygen contained in the molten tin reacts with the hydrogen to produce water (H ₂ O), to remove the oxygen contained in the molten tin of the float glass Manufacturing method. The method according to claim 1, wherein the step c) is to heat the molten tin from which oxygen is removed, and then to return to the molten tin bath. The method of claim 9, wherein the temperature of the heated molten tin is 1200 ~ 1400 ℃. The method of claim 1, wherein in the step c), the molten tin from which the oxygen is removed is returned to a region where the temperature of the molten tin is 1200 to 1400 ° C in all regions of the molten tin bath. In the float glass manufacturing apparatus for manufacturing a float glass by floating the glass over the molten tin contained in the molten tin bath, Molten tin bath; A discharge line connected to communicate with the inside of the molten tin bath and discharging a part of the molten tin of the molten tin bath to the outside of the molten tin bath; An oxygen removal chamber provided to be connected to the discharge line to receive the molten tin discharged from the molten tin bath through the discharge line; An injector provided inside the oxygen removal chamber and injecting an oxygen removal gas including hydrogen to the molten tin in the oxygen removal chamber; And And a return line for returning the molten tin from which oxygen has been removed by the injector to the molten tin bath. The apparatus of claim 12, wherein the discharge line is connected to a region in which the temperature of the molten tin is 700 to 1000 ° C. in all the regions of the molten tin bath. The method of claim 12, wherein the injector, by lowering the temperature of the molten tin in the oxygen removal chamber to reduce the saturated solubility of oxygen contained in the molten tin so that the oxygen contained in the molten tin can be removed, Apparatus for producing a float glass which is a bubbling device for bubbling the oxygen removal gas comprising a bubbled molten tin contained in the oxygen removal chamber. The method according to claim 14, for manufacturing a float glass that the bubbling device, as of 0.2 ~ 2Nm ³ / hr flow rate, a 2 to a pressure of 5kgf / cm ^2, the temperature is supplied to the oxygen removal 300 ~ 500 ℃ gas Device. The apparatus of claim 12, wherein the oxygen removing gas further comprises an inert gas. The apparatus for producing float glass according to claim 16, wherein a mixing ratio of the inert gas and the hydrogen gas of the oxygen removing gas is less than 90 to 100: more than 0 to 10 on a volume basis. The apparatus of claim 14, wherein the bubbling device comprises a porous member. 19. The apparatus of claim 18, wherein the hole formed in the porous member is formed to be inclined with respect to a vertical line perpendicular to the plate surface of the porous member. The apparatus of claim 18, wherein the porous member is formed of a ceramic material. The apparatus of claim 14, further comprising a gas supply line connected to the oxygen removing chamber and supplying the oxygen removing gas bubbled by the bubbling device into the oxygen removing chamber. The apparatus for producing float glass according to claim 14, wherein a temperature of the molten tin in the oxygen removing chamber bubbled by the bubbling device is 400 to 700 ° C. The method of claim 12, wherein the oxygen contained in the molten tin in the oxygen removal chamber and the hydrogen is reacted to produce water (H ₂ O), the oxygen contained in the molten tin to remove the Manufacturing equipment. The apparatus for manufacturing float glass according to claim 23, wherein the oxygen removal chamber is provided with a discharge port through which the water (H ₂ O) is discharged to the outside of the oxygen removal chamber in the form of water vapor. The method of claim 12, further comprising a heating chamber provided to be connected to the oxygen removal chamber, including a heating device for heating the molten tin from which oxygen is removed from the oxygen removal chamber, The return line is provided to connect the heating chamber and the molten tin bath to return the molten tin heated in the heating chamber to the molten tin bath. The apparatus of claim 25, wherein the molten tin heated in the heating chamber is 1200 to 1400 ° C. The method according to claim 25, wherein the heating chamber and the oxygen removal chamber is integrally divided into partitions of the heating chamber and the oxygen removal chamber by a partition wall, The partition wall has a through-hole is formed so that the molten tin from which the oxygen is removed from the oxygen removal chamber is moved to the heating chamber. 28. The apparatus of claim 27, wherein the through hole is formed in the partition wall so as to be positioned at a position lower than the level of the molten tin contained in the oxygen removing chamber. The apparatus of claim 12, wherein the return line returns the molten tin from which the oxygen is removed to a region in which the temperature of the molten tin is 1200 to 1400 ° C. in all regions of the molten tin bath.

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